Bug 985728 - Improve storage access time by leveraging indices

Added helper methods to DB to look up object by indices or key.
Changed sync processing loop and other places to use index/key look up.
Bug 986726 - Disable Evernote sync feature if Gecko version does not support auth process
Merge pull request #17 from yor-mozilla-com/fix986726

Bug 986726 - Disable Evernote sync feature if Gecko version does not sup...
Merge pull request #16 from yor-mozilla-com/fix985728

Bug 985728 - Improve storage access time by leveraging indices